As described in the Patent Document 1, in a seat lifter for raising or lowering a seat cushion that is provided on a vehicle seat, there is known a structure in which a sector is welded and fixed to a tubular shaft member inserted into bearing holes of a pair of side panels via bushings to be freely rotatable.
Also, with respect to this structure, outwardly fitting a ring shaped spacer to the tubular shaft member between the sector and the side panel, while adding a structure for biasing the tubular shaft member in a direction for making the sector and the side panel to approach is also carried out to generate torques (a static torque and a dynamic torque) by sliding friction forces between the spacer and the sector and bushings, that are caused by a rotation of the sector in conjunction with a lifting operation.    Patent Document 1: Japanese Patent Application Publication No. 2007-202627
By the way, the conventional seat lifter structure was a structure where which one of the sector and the bushings is going to slide with the spacer is not determined when the sector is rotated by the operation of the lifter. For this reason, there was a room for improvement in that it is hard to stabilize the torques (a static torque and a dynamic torque) at a time of rotating the sector.
On the other hand, thinning of the tubular shaft member is also discussed in conjunction with making the seat light-weighted. However, when the tubular shaft member is thinned, the welding of the sector becomes difficult, so that it was necessary to fix the sector to the tubular shaft member by a method other than the welding.
For this reason, it has been expected that the improvement to stabilize torques at a time of rotating the sector is realized in a structure for fixing the sector to the tubular shaft member by a method other than the welding.